The Molecular and Structural Basis of O -methylation Reaction in Coumarin Biosynthesis in Peucedanum praeruptorum Dunn
Methoxylated coumarins represent a large proportion of officinal value coumarins while only one enzyme specific to bergaptol -methylation (BMT) has been identified to date. The multiple types of methoxylated coumarins indicate that at least one unknown enzyme participates in the -methylation of othe...
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Veröffentlicht in: | International journal of molecular sciences 2019-03, Vol.20 (7), p.1533 |
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Zusammenfassung: | Methoxylated coumarins represent a large proportion of officinal value coumarins while only one enzyme specific to bergaptol
-methylation (BMT) has been identified to date. The multiple types of methoxylated coumarins indicate that at least one unknown enzyme participates in the
-methylation of other hydroxylated coumarins and remains to be identified. Combined transcriptome and metabonomics analysis revealed that an enzyme similar to caffeic acid
-methyltransferase (COMT-S, S is short for similar) was involved in catalyzing all the hydroxylated coumarins in
. However, the precise molecular mechanism of its substrate heterozygosis remains unsolved. Pursuing this question, we determined the crystal structure of COMT-S to clarify its substrate preference. The result revealed that Asn132, Asp271, and Asn325 govern the substrate heterozygosis of COMT-S. A single mutation, such as N132A, determines the catalytic selectivity of hydroxyl groups in esculetin and also causes production differences in bergapten. Evolution-based analysis indicated that BMT was only recently derived as a paralogue of caffeic acid
-methyltransferase (COMT) via gene duplication, occurring before the Apiaceae family divergence between 37 and 100 mya. The present study identified the previously unknown
-methylation steps in coumarin biosynthesis. The crystallographic and mutational studies provided a deeper understanding of the substrate preference, which can be used for producing specific
-methylation coumarins. Moreover, the evolutionary relationship between BMT and COMT-S was clarified to facilitate understanding of evolutionary events in the Apiaceae family. |
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ISSN: | 1422-0067 1661-6596 1422-0067 |
DOI: | 10.3390/ijms20071533 |